A light-emitting diode (LED) often can provide light in a more efficient manner than an incandescent light source and/or a fluorescent light source. The relatively high power efficiency associated with LEDs has created an interest in using LEDs to displace conventional light sources in a variety of lighting applications. For example, in some instances LEDs are being used as traffic lights and to illuminate cell phone keypads and displays.
Typically, an LED is formed of multiple layers, with at least some of the layers being formed of different materials. In general, the materials and thicknesses selected for the layers determine the wavelength(s) of light emitted by the LED. In addition, the chemical composition of the layers can be selected to try to isolate injected electrical charge carriers into regions (commonly referred to as quantum wells) for relatively efficient conversion to optical power. Generally, the layers on one side of the junction where a quantum well is grown are doped with donor atoms that result in high electron concentration (such layers are commonly referred to as n-type layers), and the layers on the opposite side are doped with acceptor atoms that result in a relatively high hole concentration (such layers are commonly referred to as p-type layers).
LEDs also include contact structures (also referred to as electrical contact structures or electrodes), which are features on a device that are electrically connected to a power source. The power source can provide current to the device via the contact structures, e.g., the contact structures can deliver current along the lengths of structures to the surface of the device where energy can be converted into light.
In some devices, problems may arise when the contact structures do not spread current uniformly across the surface of the device. This can lead to undesirable effects such as non-uniform light emission across the device, decreased light output, overheating, and performance degradation.
Contact structures that would, for example, minimize these effects in LEDs would find application in a number of different fields.